A magnetic disk drive apparatus is an apparatus for recording and reading data on the surfaces of spinning disks through the use of a changing magnetic field. One or more data storage disks are coaxially mounted on a hub of a spindle motor. The spindle motor rotates the disks at speeds typically on the order of several thousand to tens of thousands of revolutions-per-minute. Digital information, representing various types of data, is typically written to and read from the data storage disks by one or more transducers, or read/write heads, which are mounted to an actuator assembly and hover above the surface of the rapidly rotating disks.
The transducer head is typically in the form of a magnetoresistive (MR) head or element carried on a slider body. Oftentimes, the slider and transducer are designated as a “head”. Regardless, the slider body is mounted to a flexible suspension portion of an arm assembly that is otherwise part of the actuator assembly. Upon final assembly, the actuator assembly positions the slider over a surface of a disk. The slider is configured such that as the disk rotates, an air bearing develops between the slider and the disk surface, causing the slider, and thus the read and write elements, to lift and fly several micro inches above the disk surface. The distance between the slider and the disk surface is often times referred to as a “fly height”. In magnetic recording technology, it is desired to “fly” the slider as closely as possible to the disk surface (i.e., minimal fly height) so that the read transducer can distinguish between the magnetic fields emanating from closely spaced regions on the disk.
Disk drive manufacturers constantly strive to improve upon the slider design to provide a minimized fly height, along with the satisfying other constraints as slider roll, pitch, and skew. These features are typically accomplished by forming (e.g., etching) aerodynamic rails or pads into the slider body. These rails must be machined to exacting standards, and constitute permanent structures. That is to say, the rails or pads will not erode or otherwise change shape upon expected or unexpected contact with the disk surface. In contrast, a recently developed slider configuration incorporates a burnishable rear pad. Unlike traditional slider rail or pad constructions, a burnishable rear pad slider design relies upon reshaping of the rear pad upon contact with the rotating disk to achieve a final shape and fly height.
As a point of reference, the rear pad of a burnishable rear pad slider maintains the read and/or write elements. During manufacture, the rear pad is formed to have generally linear or planar side and bottom surfaces, and may have an enlarged height or thickness. More particularly, in conjunction with other disk drive parameters, including configuration of the actuator arms and other slider components, such as a slider body support structure, the rear pad is normally formed to a thickness slightly greater than the expected final thickness that would otherwise produce a desired a fly height. In other words, upon final assembly of the disk drive and initial rotation of the disk at normal operation speeds, the rear pad continues to contact or rub against the relevant disk surface. Because the rear pad is made of a burnishable material, continued contact between the rear pad and the rotating disk burnishes the rear pad, thereby reducing its height. In theory, this burnishing procedure continues until the rear pad thickness has been reduced to a point where rear pad just begins to fly relative to the disk surface. This results in fly height that theoretically is as small as possible.
The above-described burnishable rear pad slider design appears highly viable. The exacting manufacturing tolerances required of conventional slider pad or rail designs is eliminated, and a highly minimized fly height can be achieved. However, opportunities for improvement exist. The current technique for burnishing the rear pad produces a rear pad height profile that is essentially co-planar with the disk surface. For disk drive applications, this shape is less than aerodynamically optimal.
Burnishable rear pad slider technology represents a distinct advancement in the disk drive art. Certain opportunities exist for perfecting implementation of this technology, including an optimal burnishment methodology. Therefore, a need exists for a method of optimally burnishing or shaping a burnishing rear pad slider.